Wrist architecture

ABSTRACT

A method of using a medical instrument can include applying a distally-directed or proximally-directed load via a drive member to an end effector coupled to an elongated shaft via a wrist assembly so as to actuate the end effector; and reacting the distally-directed or proximally-directed load to an inner link of the wrist assembly that is pivotally coupled to a first outer link and a second outer link. The wrist assembly can be actuatable via drive cables and reacting the load maintains the first outer link interfaced with the second outer link in the absence of tension in the drive cables.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.17/569,595, filed Jan. 6, 2022, which is a continuation of U.S.application Ser. No. 16/331,672, filed Mar. 8, 2019 (now U.S. Pat. No.11,234,700), which is a U.S. National Stage Application ofPCT/US2017/050754, filed Sep. 8, 2017 (now expired), which claims thebenefit of U.S. Application No. 62/385,621, filed Sep. 9, 2016 (nowexpired); each of which are incorporated by reference herein in theirentirety.

BACKGROUND

Minimally invasive surgical techniques are aimed at reducing the amountof extraneous tissue that is damaged during diagnostic or surgicalprocedures, thereby reducing patient recovery time, discomfort, anddeleterious side effects. As a consequence, the average length of ahospital stay for standard surgery may be shortened significantly usingminimally invasive surgical techniques. Also, patient recovery times,patient discomfort, surgical side effects, and time away from work mayalso be reduced with minimally invasive surgery.

A common form of minimally invasive surgery is endoscopy, and a commonform of endoscopy is laparoscopy, which is minimally invasive inspectionand/or surgery inside the abdominal cavity. Reloadable stapling devicescan be used in conjunction with these surgeries. Telesurgicallycontrolled stapling devices can include servo controlled wrist jointsthat yaw and pitch at relatively extreme angles (e.g., up to and over 90degrees). Such joints can place a large amount of strain on actuationcomponents that must translate through the wrist at such angles.Accordingly, current actuation devices are often limited by the abilityof actuation components to function under extreme angles.

BRIEF SUMMARY

Embodiments disclosed herein relate to surgical devices having wriststhat can yaw and pitch at relatively large angles. Such wrists can havea yaw axis spatially separated from a pitch axis, with both such axesbeing perpendicular to one another as well as a longitudinal axis thatdefines the extension of an arm or shaft of a telesurgically controlleddevice. In some cases, the yaw and pitch angles can be up to 45, 60, or90 degrees.

Such pitch and yaw angles require an extremely flexible actuationmechanism for opening and closing jaws of the surgical device andoptionally actuating other implements such as cutting and/or staplingdevices. In some embodiments, an actuation mechanism can include apushing component. The pushing component can be adapted to be highlycompressible under extreme angles, while being extremely flexible. Thepushing component may not however, be well suited to tensile forces.Accordingly a separate pulling component can be used to apply tensileforce for proximal movement and actuation of the surgical device. In asimilar manner, the pulling component may not be well suited forcompressive forces. However, the combination of the pushing and pullingcomponent into one integrated device can be effectively used for bothcompressive and tensile force application (i.e., pushing and pulling) toactuate components of an end effector of a surgical device.

The pushing component and the pulling component can be integrated alonga shared axis with the pushing component being concentrically arrangedabout the pulling component. In some embodiments, the pushing componentincludes a coiled spring and the pulling component includes a braidedcable. Alternatively the pulling component can be concentricallyarranged about the pushing component.

To enable a high degree of wrist flexibility, the wrist assembly can beconstructed from outer links that define yaw and pitch geometry for thewrist assembly. The outer links can house a flexible portion of theactuation mechanism. However, compression of the actuation mechanismwithin a wrist can cause buckling and decrease efficiency of forcetransmission. To help mitigate such issues, inner links can be providedthat connect the outer links to one another. The inner links can definea passage that constrains and limits lateral movement of the actuationmechanism, and thus mitigate buckling.

Thus, in one aspect, an apparatus includes an elongated shaft, an endeffector, and a wrist assembly. The elongated shaft extends along afirst axis. The end effector includes an upper jaw and a lower jaw. Thewrist assembly moveably connects the end effector to the elongatedshaft. The wrist assembly includes a first outer link, a first innerlink, and a second outer link. The first outer link is connected to theelongated shaft and movably coupled to the second outer link by thefirst inner link. The first outer link, the first inner link, and thesecond outer link define a proximal joint. A medial surface of the firstouter link and a medial surface of the second outer link define a lumenin which the first inner link is disposed. The medial surface of thefirst outer link defines at least a first recess and the medial surfaceof the second outer link defines at least a second recess. A radialsurface of the first inner link includes at least a first protrusion anda second protrusion. The first protrusion of the first inner linkengages the first recess. The second protrusion of the inner linkengages the second recess.

In some embodiments of the apparatus, the wrist assembly is operable toreorient to the end effector relative to the elongated shaft about anaxis that is perpendicular to the first axis. For example, in someembodiments of the apparatus, the proximal joint extends along a secondaxis that is perpendicular to the first axis.

In some embodiments of the apparatus, the wrist assembly is operable toreorient to the end effector relative to the elongated shaft about eachof two axes that are perpendicular to the first axis. For example, thewrist assembly can further include a second inner link and a third outerlink. The third outer link is connected to the end effector and moveablycoupled to the second outer link by the second inner link. The thirdouter link, the second inner link, and the second outer link define adistal joint. The wrist assembly can be configured to yaw and pitch atthe proximal and distal joints, respectively. In some embodiments of theapparatus, each of the first inner link and the second inner linkincludes first and second clevis protruding journals.

In some embodiments of the apparatus, the wrist assembly has an interiorpassage through which an actuation component extends. For example, someembodiments of the apparatus include an elongated drive member drivinglycoupled with the end effector and extending through an interior passagedefined by the first inner link. In some embodiments of the apparatus,the elongated drive member is operable to apply a distally directedforce to the end effector. In some embodiments, the interior passage isclosely formed about the elongated drive member to prevent the elongateddrive member from buckling while applying the distally directed force tothe end effector. In some embodiments, the wrist assembly includes aninner sheath within the interior passage through which the elongateddrive member extends.

In some embodiments of the apparatus, the first outer link and thesecond outer link interface so as to control relative orientationbetween the first outer link, the first inner link, and the second outerlink during articulation of the wrist assembly. For example, in someembodiments, the first outer link and the second outer link includeintermeshing gear teeth that control relative orientation between thefirst outer link, the first inner link, and the second outer linkthrough a range of orientations between the second outer link and thefirst outer link. In some embodiments, the first inner link is passivelyconstrained by the first outer link and the second outer link.

In another aspect, an apparatus includes an elongated arm, and endeffector, an elongated drive member, and a wrist assembly. The elongatedarm extends along a first axis.

The end effector includes an upper jaw and a lower jaw. The elongateddrive member extends from the elongated arm and is drivingly coupledwith the end effector for actuation of the end effector. The wristassembly moveably connects the elongated arm to the end effector. Thewrist assembly includes a plurality of outer links and a plurality ofinner links. The wrist assembly is operable to yaw and pitch the endeffector relative to the elongated arm. The inner links define an innerpassage between the elongated arm and the end effector through which theelongated drive member extends.

In some embodiments of the apparatus, the wrist assembly is operable toreorient to the end effector relative to the elongated shaft about anaxis that is perpendicular to the first axis. For example, in someembodiments of the apparatus, the wrist assembly includes a proximaljoint that extends along a second axis perpendicular to the first axis.

In some embodiments of the apparatus, the wrist assembly is operable toreorient to the end effector relative to the elongated shaft about eachof two axes that are perpendicular to the first axis. For example, thewrist assembly can further include a distal joint that extends along athird axis perpendicular to the first axis and the second axis. In someembodiments, the wrist assembly is configured to yaw at the proximaljoint and pitch at the distal joint. In some embodiments, each of theinner links comprises first and second protruding journals.

In some embodiments of the apparatus, the wrist assembly has an interiorpassage through which an actuation component extends. For example, someembodiments of the apparatus, the interior passage is closely formedabout the elongated drive member to prevent the elongated drive memberfrom buckling under compression. In some embodiments, the wrist assemblyincludes an inner sheath within the interior passage and through whichthe elongated drive member extends.

In some embodiments of the apparatus, the outer links interface so as tocontrol relative orientation between the outer links and the innerlinks. For example, in some embodiments, the outer links includeintermeshing gear teeth that control relative orientation between theouter links and the inner links through a range of orientations betweenthe outer links. In some embodiments, the inner links are passivelyconstrained by the outer links.

In some embodiments, the wrist assembly is actuated via tension members.For example, in some embodiments, the apparatus includes cable portionsthat extend through portions of the outer links and are articulated toarticulate the wrist assembly.

In another aspect, a surgical device includes an elongated shaft, an endeffector, and a wrist assembly. The elongated shaft extends along afirst axis. The end effector includes an upper jaw and a lower jaw. Thewrist assembly moveably connects the end effector to the elongatedshaft. The wrist assembly includes a first outer link, a first innerlink, and a second outer link. The first outer link is connected to theelongated shaft and includes first gear teeth. The first inner link ispivotally coupled with the first outer link to rotate relative to thefirst outer link around a second axis oriented perpendicular to thefirst axis. The second outer link is pivotally coupled with the firstinner link to rotate relative to the first inner link around a thirdaxis parallel to the second axis and offset from the second axis. Thesecond outer link includes second gear teeth that interface with thefirst gear teeth and control orientation of the first inner linkrelative to the first outer link and the first outer link throughout arange of orientations of the second outer link relative to the firstouter link.

The first inner link can be pivotally coupled with the first outer linkand the second outer link using any suitable pivot connection. Forexample, in some embodiments of the surgical device: the first innerlink includes a first pair of protruding journals aligned with thesecond axis and a second pair of protruding journals aligned with thethird axis, the first outer link comprises a pair of first outer linkjournal bearings interfacing with the first pair of protruding journals,and the second outer link comprises a pair of second outer link journalbearings interfacing with the second pair of protruding journals.

The first inner link, the first outer link, or the second outer link canhave a multiple-piece construction to facilitate assembly of the wristassembly. For example, in some embodiments of the surgical device, thefirst inner link has a multiple-piece construction comprising a firstinner link first portion and a first inner link second portion. In someembodiments of the surgical device, the first inner link first portionand the first inner link second portion are configured to be interfacedwith one of the first outer link and the second outer link via rotationof each of the first inner link first portion and the first inner linksecond portion relative to the one of the first outer link and thesecond outer link. In some embodiments of the surgical device, the otherof the one of the first outer link and the second outer link has amultiple-piece construction adapted to accommodate assembly to the firstinner link after the first inner link is assembled with the one of thefirst outer link and the second outer link.

In some embodiments of the surgical device, the wrist assembly forms anaperture through which an actuation assembly extends. For example, insome embodiments, the first inner link forms the aperture and thesurgical device includes an elongated drive member that extends throughthe aperture and is drivingly coupled with the end effector to actuate amechanism of the end effector.

In some embodiments of the surgical device, the wrist assembly is cabledriven and configured to react both proximally-directed loads anddistally-directed loads applied to the end effector without relying oncable tension to react the distally-directed loads to keep the wristassembly components from separating. For example, in some embodiments,the surgical device includes cable portions drivingly coupled with thewrist assembly and articulated to articulate the wrist assembly and thefirst inner link is configured to react both tension and compressionloads applied to the end effector by the drive member back to the firstouter link so as to keep the second outer link interfaced with the firstouter link even in the absence of any of the cable portions being undertension.

In some embodiments of the surgical device, the wrist assembly isoperable to reorient to the end effector relative to the elongated shaftabout each of two axes that are perpendicular to the first axis. Forexample, the wrist assembly can further include a second inner link anda third outer link. The second inner link can be pivotally coupled withthe second outer link to rotate relative to the second outer link arounda fourth axis oriented perpendicular to the first axis and to the thirdaxis. The third outer link can be pivotally coupled with the secondinner link to rotate relative to the second inner link around a fifthaxis parallel to the fourth axis and offset from the fourth axis. Thethird outer link can include gear teeth that interface with gear teethof the second outer link and control orientation of the second innerlink relative to the third outer link and the second outer linkthroughout a range of orientations of the third outer link relative tothe second outer link.

The second inner link can be pivotally coupled with the second outerlink and the third outer link using any suitable pivot connection. Forexample, in some embodiments of the surgical device: the second innerlink includes a first pair of protruding journals aligned with thefourth axis and a second pair of protruding journals aligned with thefifth axis, the second outer link includes a pair of second outer linkjournal bearings interfacing with the first pair of protruding journalsof the second inner link; and the third outer link includes a pair ofthird outer link journal bearings interfacing with the second pair ofprotruding journals of the second inner link.

The second inner link, the second outer link, or the third outer linkcan have a multiple-piece construction to facilitate assembly of thewrist assembly. For example, in some embodiments of the surgical device,the second inner link has a multiple-piece construction comprising asecond inner link first portion and a second inner link second portion.In some embodiments, the second inner link first portion and the secondinner link second portion are configured to be interfaced with one ofthe second outer link and the third outer link via rotation of each ofthe second inner link first portion and the second inner link secondportion relative to the one of the second outer link and the third outerlink. In some embodiments, the other of the one of the second outer linkand the third outer link has a multiple-piece construction adapted toaccommodate assembly to the second inner link after the second innerlink is assembled with the one of the second outer link and the thirdouter link.

In some embodiments of the surgical device, the wrist assembly forms anaperture through which an actuation assembly extends. For example, insome embodiments, the second inner link forms a second inner linkaperture. The surgical device can include an elongated drive member thatextends through the second inner link aperture and is drivingly coupledwith the end effector to actuate a mechanism of the end effector.

In some embodiments of the surgical device, the wrist assembly is cabledriven and configured to react both proximally-directed loads anddistally-directed loads applied to the end effector without relying oncable tension to react the distally-directed loads to keep the wristassembly components from separating. For example, the surgical devicecan include cable portions drivingly coupled with the wrist assembly andarticulated to articulate the wrist assembly. The first inner link andthe second inner link can be configured to react both tension andcompression loads applied to the end effector by the drive member backto the first outer link so as to keep the third outer link interfacedwith the second outer link and the second outer link interfaced with thefirst outer link even in the absence of any of the cable portions beingunder tension.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1C show views of a surgical tool, according to manyembodiments.

FIGS. 2A, 2B, and 2C shows a perspective, side, and bottom views of asurgical tool, according to many embodiments.

FIGS. 3A and 3B show cross-sectional views of a surgical tool, accordingto many embodiments.

FIG. 4A shows a perspective view of an actuation mechanism, according tomany embodiments.

FIG. 4B shows a cross-sectional view of an actuation mechanism,according to many embodiments.

FIGS. 4C and 4D show perspective views of pushing members, according tomany embodiments.

FIG. 4E shows a cross-sectional view of an actuation mechanism,according to many embodiments.

FIG. 5A shows a perspective view of a wrist assembly, according to manyembodiments.

FIG. 5B shows a cross-sectional view of a wrist assembly, according tomany embodiments.

FIG. 5C shows a perspective view of an outer link assembly, according tomany embodiments.

FIGS. 6A-6C show a method of assembling a wrist assembly, according tomany embodiments.

DETAILED DESCRIPTION

FIGS. 1A-1C show a surgical tool 10 that includes a proximal chassis 12,an instrument shaft 14, and a distal end effector 16 having an upper jaw18 that can be articulated to grip a patient tissue. The proximalchassis 12 includes input couplers 22 that may interface with and bedriven by corresponding output couplers of a telesurgical surgerysystem, such as the system disclosed within Pub. No. US 2014/0183244 A1,which is incorporated by reference herein. The input couplers 22 aredrivingly coupled with one or more input members that are disposedwithin the instrument shaft 14. The input members are drivingly coupledwith the end effector 16. As shown at FIGS. 1B and 1C, input couplers 22of the proximal chassis 12 can be adapted to mate with various types ofmotor packs 13, such as stapler specific motor packs disclosed at U.S.Pat. No. 8,912,746, or the universal motor packs disclosed at U.S. Pat.No. 8,529,582, which are incorporated by reference herein.

FIGS. 2A-2C show perspective, side, and top views of a distal end of thesurgical tool 10 including the end effector 16. End effector 16 ismoveably connected to the instrument shaft 14 by a wrist assembly 24.The wrist assembly 24 has at least two degree of freedom and providesfor attachment of the end effector 16 to the elongated instrument shaft14 for articulation of the end effector 16 about two orthogonal axesrelative to the instrument shaft 14. The wrist assembly 24 is configuredto yaw about axis 2-2, which is perpendicular to axis 1 that theinstrument shaft 14 extends along. The wrist assembly 24 is alsoconfigured to pitch about axis 3, which is perpendicular to axis 1 andaxis 2. As shown, the yaw axis 2 is proximal (farther from the endeffector 16) to the pitch axis 3, however this is not a requirement andin some embodiments the yaw axis 2 is distal to the pitch axis 3.

FIGS. 3A and 3B are a cross-sectional views showing details of endeffector 16 that include the upper jaw 18 and a lower jaw 26. The lowerjaw 26 can be configured to accommodate and support a removable ornon-removable stapling cartridge. The upper jaw 18 is pivotally coupledwith the lower jaw 26 to articulate relative to the lower jaw 26 toclamp tissue. A beam member 28 is driven from a proximal state shown atFIG. 3A to a distal state shown at FIG. 3B to actuate the upper jaw 18.Movement of the beam member 28 can serve to forcibly secure the upperjaw 18 over tissue with respect to the lower jaw 16. Optionally, thebeam member 28 can also allow for cutting tissue and deploying staplesfrom the cartridge into the cut tissue.

The beam member 28 includes an upper beam portion 30 that is configuredto slide within a rail feature 32 of the upper jaw 18. The rail feature32 includes a ramp 34 for the upper beam portion 30 to engage from aproximal most garage area 36. The open position shown at FIG. 3A can bemaintained by a resilient device, such as a spring, or opened and closedby a secondary mechanism (not shown). Partial closure of the upper jaw18 can be affected by distal movement of the upper beam portion 30 ontothe ramp 34. Complete closure of the upper jaw 18 is achieved when theupper beam portion 30 is moved distally past the ramp 34 and onto therail feature 32. Proximal movement of the upper beam portion 30 off ofthe ramp 34 removes the closure force applied by the beam member. Aresilient device or secondary mechanism can then cause a closed orpartially closed upper jaw 18 to open. Thus, back and forth movement ofthe upper beam portion 30 along the ramp 34 can toggle the end effector16 open and closed.

The beam member 28 also includes a lower beam portion 38 that configuredto slide within a rail feature 32 of the lower jaw 18. The lower beamportion 38 can actuate a sled (such as disclosed in Pub. No. US2014/0183244 A1) configured for ejecting staples out the lower jaw 26during distal movement of the beam member 28. Alternatively, the lowerbeam portion 30 can be integrated with such a sled.

FIG. 4A shows a perspective view of the beam member 28. Here, the upperbeam portion 30 includes an integrated cutting member 40 that isconfigured to cut tissue. However, in other embodiments a tissue cuttingdevice can be separate from the beam member 28 or implemented into thebeam member 28 in a different manner. The upper beam portion 30 includesan upper flange 42, which transversely extends from the integratedcutting member 40. The gliding portion 42 is configured to directlyinterface with the rail feature 32 and ramp 34. In a similar manner alower flange 44 is provided to slide with a rail feature of the lowerjaw 26. An elongated drive member 46 is attached to the beam member 28for providing distal and proximal movement to the drive member 46.

FIG. 4B shows a cross-sectional view of the beam member 28 and drivemember 46. The drive member 46 includes a pushing member 48 and apulling member 50. The pushing member 48 is configured as a close-coiledspring and is adapted for translating axial force applied by a drive rod52. The pushing member 48 can be externally constrained by a sheath 54,which can be constructed from a lubricous polymer material such as PTFE.The coiled design of the pushing member 48 allows compressive force tobe translated effectively to the beam member 28 to push the beam member28 in the distal direction. The pushing member 48 can be constructedfrom a coiled wire in the conventional manner or be spirally cut from atube. In some cases, the compressive elements (e.g., coils) of thepushing member will separate under tension, and thus in such cases thepushing member can only be effective for transfer of compressive forces.

The pulling member 50 can be constructed from a braided cable or otherflexible rod and retained within the beam member 28 by crimp portion 56.In some cases, the pulling member may be relatively ineffective fortransfer of pushing forces as it can have the tendency to collapse orbuckle on itself, and thus in such cases the pulling member can only beeffective for transfer of tensile forces. The pulling member 50 is alsoadapted for translating axial force applied by a drive rod 52. The driverod 52 is located within the instrument shaft 14 and is drivinglycoupled to one or more of the input couplers 22 shown at FIG. 1 . Thepulling member 50 allows tensile force to be translated effectively fromthe drive rod 52 to the beam member 28, to pull the beam member 28 inthe proximal direction. The pushing member 48 and pulling member 50operate in a complementary manner to provide distal and proximal motionto the beam member 28 by segregating tensile forces to the pullingmember 50 and the compressive forces to the pushing member 48. Thisenables a very flexible and compact design for the drive member 46,characteristics that enable the drive member 46 to translate within thewrist 24, which can be disposed at torturous yaw and pitch angles duringoperation.

The pushing member is not limited to a close-coiled spring design asdepicted at FIG. 4B. For example, a flexible pushing member 58 as shownat FIG. 4C can be formed from a solid tube by cutting a pattern into thesolid tube to increase bending flexibility at the wrist withoutmaterially decreasing compressive stiffness. Here, the pushing member 58is formed by laser cutting a pattern into a metal tube. The pattern hereallows for flexibility where gaps are formed in the tube and axialstiffness where material is left in place. Another example of a flexiblepushing member is depicted at FIG. 4D, which shows a pushing member 60having a plurality of circumferential slits arranged in a spiralingpattern.

FIG. 4E shows an alternative configuration of a drive member 60. Theconfiguration here is the opposite as what is depicted at FIG. 4B inwhich the pushing member 48 is concentrically surrounds the pullingmember 50. Here, the drive member includes a pulling member 62configured as an braided sheath that encapsulates a pushing member 64.The pushing member 64 is configured as a plurality of spherical members(e.g., ball bearings) joined by a flexible rod 66. Both the pushingmember 64 and pulling member 62 are actuated by the drive rod 52, whichis drivingly coupled to one or more of the input couplers 22 shown atFIG. 1 .

FIGS. 5A and 5B show perspective and cross-sectional views of the wristassembly 24. The wrist assembly 24 includes a proximal outer link 100, amiddle outer link 102, and a distal outer link 104. These three linksdetermine the kinematic pitch and yaw motion of the wrist assembly 24.As shown, the interface between the proximal outer link 100 and themiddle outer link 102 determine yaw movement of the wrist assembly 24.The interface between the outer distal link 104 and the middle outerlink 102 determine pitch movement of the wrist assembly 24. However, inan alternative wrist configuration, this relationship can be reversedsuch that the wrist assembly 24 pitches between the proximal outer link100 and the middle outer link 102 and yaws between the distal outer link100 and the middle outer link 102 (e.g., by rotating the end effector 16relative to wrist assembly 24 by 90 degrees).

Cable portions 106 are drivingly coupled with the wrist assembly 24 andactuated to impart motion to the wrist assembly 24. In some embodiments,cable portions 106 can be individually secured to a portion of thedistal outer link 104. In an functionally equivalent alternateembodiment, as shown at FIG. 5A, cable portions 106 are looped about aportion of the distal outer link 104 as shown. Looping cable portions106 to the distal outer link 104 can be used to secure the cableportions 106 to the distal outer link 104. The cable portions 106 can bearticulated to articulate the wrist assembly 24. Differential movementof the cable portions 106 can be used to actuate the wrist assembly 24to pitch and yaw at various angles. The cable portions 106 can bedrivingly coupled to one or more of the input couplers 22 shown at FIG.1 . The wrist assembly also includes proximal inner link 108 and distalinner link 110, which are discussed in detail below.

With attention to FIG. 5C, an exemplary embodiment of a joint 112 isshown that is representative of the interfaces between the outer linksshown at FIGS. 5A and 5B. The joint 112 includes a first link 114 and asecond link 116. First link 114 may include gear teeth 118, 120 and abearing projection 122. The second link 116 includes gear teeth 124,126, 128 and a bearing projection 130. According to an exemplaryembodiment, projections 122, 130 of first and second links 114, 116 mayinclude passages to permit cable portions 106 to pass through. Becausebearing projections 122, 130 are located at an outboard locationrelative to central apertures 134, 136 cable portions 106 extendingthrough passages adjacent to bearing projections 122, 130 also arelocated at an outboard location. This allows for routing of othermechanisms through the central apertures 134, 136. Actuation kinematicsbetween the links 114, 116 are determined by the shape of the gear teeth118, 120, 124, 126, 128, which engage and disengage during movement. Thebearing projections 122, 130 included curved surfaces that can engage atsuitable point throughout all angular motion to help reduce compressivestrain to the gear teeth 118, 120, 124, 126, 128.

Due to the enhanced range of motion provided by joint 112, a wristincluding joint 112 may provide a desired amount of motion, such as+/−90 degrees in a pitch or yaw direction, in a more efficient mannerwith fewer parts. In previous wrist structures in which each joint islimited to a maximum roll angle of about 45 degrees, several such jointsin series are needed to achieve relatively large roll angle for theentire wrist mechanism. In the illustrated embodiment, a single joint112 can provide up to a 90 degree angular deflection. As a result,manufacturing cost and complexity for a wrist that includes one or morejoints 112 may be reduced while still achieving desired angulardeflection. In addition, the gear teeth 118, 120, 124, 126, 128 includedin links 114, 116 of joint 112 can provide enhanced timing to assistwith accurately positioning links 114, 116, including, for example,returning links 114, 116 to a neutral position (e.g., zero angle rollalignment), and to enhance smoothness of the motion between links 114,116, such as when links 114, 116 are reoriented relative to one another.According to an exemplary embodiment, a wrist may include a plurality ofjoints 112 to achieve higher ranges of motion (up to roll limit angles),such as, for example, wrists having a range of motion of up to +/−180degrees in a pitch or yaw direction. Additional details of joint 112,and other joints usable with the embodiments disclosed herein, aredisclosed in Intl. Pub. No. WO 2015/127250, which is incorporated byreference herein.

As shown at FIG. 5B, the proximal and distal inner links 108, 110 arespatially separated along axis 1 and offset 90 degrees from one another.Hence, the proximal internal link 108 is only partially shown. Radialsurfaces of the proximal and distal inner links 108, 110 includeprotrusions (e.g. configured as protruding journals 140). Theprotrusions interface with recesses (e.g. configured as journal bearings142) at medial surfaces of the external links. In some embodiments, theprotruding journals 140 and the journal bearings 142 set the distancesbetween the outer links, but otherwise are passive and do not alterjoint kinematics of the outer links which is determined by the geometryof the gear teeth 118, 120, 124, 126, 128. Each side of the proximal anddistal inner links 108, 110 includes a pair of commonly alignedprotruding journals 120 that interface with the journals bearings 142for a total of four protruding journals 140 per inner link 108, 110.Each pair of protruding journals 140 is separated to provide an internalpassage 144 for the drive member 46.

An additional internal sheath 146 can be used to further support thedrive member 46. The drive member 46 slides axially within the internalsheath 146. The internal sheath 146 is fixed to a distal end portion ofthe wrist assembly 24 and is flexible to bend with movement of the wristassembly 24 but does not move axially. The internal sheath 146 andinternal passage 144 provided by the inner links 108, 110 serve to guideand constrain the drive member 46 during axial movement. Internal sheath146 and inner passage 144 prevent the drive member from buckling undercompressive loading (i.e. distal movement while cutting and stapling).Prior wrist designs, such as disclosed in the aforementioned Intl. Pub.No. WO 2015/127250, rely on tensioned cables to maintain the outer linksin position. Here, when the drive member 46 moves in a distal directionthe resulting compressive force can be reacted by via the inner links108, 110, thereby preventing potential stretching and resulting loss intension in the cables 106. The protruding journals 140 of the innerlinks 108, 110 advantageously maintain the outer links in position whenthe drive member 46 moves in a distal direction, therefore maintainingthe structure of the wrist assembly 24.

Each inner link 108, 110 can have a two-piece construction as depictedat FIGS. 6A through 6C, which also depict a technique for assembling theinner links to the outer links. At FIG. 6A first link portion 108 a andsecond link portion 108 b of the proximal inner link 108 are positionedto place protruding journals 140 into journal bearings 142 of the middleouter link 102. The first link portion 108 a and second link portion 108b are inserted at angles such that gear teeth 148 of each portionintermesh to cause alignment of the portions into the formation shown atFIG. 6B. The gear teeth 148 are an assembly aid that eliminates the needfor pins or other fasteners, and are not used for movement beyondassembly. However, in some embodiments, fasteners can be used in lieu ofthe gear teeth. After the link portions 108 a, 108 b are assembled intoa complete inner proximal link 108, the proximal outer link 100 isassembled onto the remaining exposed protruding journals 140 into theformation shown at FIG. 6C. In one embodiment, as shown at FIG. 6C,proximal outer link 100 is also of two-piece construction.

Other variations are within the spirit of the present invention. Thevarious aspects, embodiments, implementations or features of thedescribed embodiments can be used separately or in any combination.Various aspects of the described embodiments associated with operationof telesurgical tools can be implemented by software, hardware or acombination of hardware and software. Thus, while the invention issusceptible to various modifications and alternative constructions,certain illustrated embodiments thereof are shown in the drawings andhave been described above in detail. It should be understood, however,that there is no intention to limit the invention to the specific formor forms disclosed, but on the contrary, the intention is to cover allmodifications, alternative constructions, and equivalents falling withinthe spirit and scope of the invention, as defined in the appendedclaims.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. The terms “comprising,” “having,” “including,” and “containing”are to be construed as open-ended terms (i.e., meaning “including, butnot limited to,”) unless otherwise noted. The term “connected” is to beconstrued as partly or wholly contained within, attached to, or joinedtogether, even if there is something intervening. Recitation of rangesof values herein are merely intended to serve as a shorthand method ofreferring individually to each separate value falling within the range,unless otherwise indicated herein, and each separate value isincorporated into the specification as if it were individually recitedherein. All methods described herein can be performed in any suitableorder unless otherwise indicated herein or otherwise clearlycontradicted by context. The use of any and all examples, or exemplarylanguage (e.g., “such as”) provided herein, is intended merely to betterilluminate embodiments of the invention and does not pose a limitationon the scope of the invention unless otherwise claimed. No language inthe specification should be construed as indicating any non-claimedelement as essential to the practice of the invention.

Preferred embodiments of this invention are described herein, includingthe best mode known to the inventors for carrying out the invention.Variations of those preferred embodiments may become apparent to thoseof ordinary skill in the art upon reading the foregoing description. Theinventors expect skilled artisans to employ such variations asappropriate, and the inventors intend for the invention to be practicedotherwise than as specifically described herein. Accordingly, thisinvention includes all modifications and equivalents of the subjectmatter recited in the claims appended hereto as permitted by applicablelaw. Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the invention unlessotherwise indicated herein or otherwise clearly contradicted by context.

What is claimed is:
 1. A method comprising: transmitting a distallydirected axial compression force in a distal direction via an endeffector drive member coupled with an end effector comprising a jawmechanism to open the jaw mechanism; and actuating wrist drive cablesconnected to a wrist assembly to articulate the wrist assembly, whereinthe wrist assembly couples the end effector to a shaft elongated along afirst axis and articulation of the wrist assembly orients the endeffector relative to the elongated shaft through a range oforientations; wherein articulation of the wrist assembly to orient theend effector comprises: controlling orientation of a first outer linkand a second outer link relative to each other by intermeshing of firstgear teeth and second gear teeth respectively associated with the firstouter link and the second outer link, rotating the first outer link anda first inner link relative to each other about a second axisperpendicular to the first axis, the first inner link being pivotallycoupled to the first outer link, and rotating the second outer link andthe first inner link relative to each other about a third axis parallelto the second axis and offset from the second axis; and wherein thefirst inner link reactions a tension or compression load applied to theend effector by the end effector drive member back to the first outerlink thereby maintaining the second outer link interfaced with the firstouter link even in the absence of any of the wrist drive cables beingunder tension.
 2. The method of claim 1, wherein the first inner link ispivotally coupled to the first and second outer links via a first pairof journals aligned with the second axis and a second pair of journalsaligned with the third axis.
 3. The method of claim 1, wherein orientingthe wrist assembly comprises orienting the wrist assembly through arange of orientations about a fourth axis perpendicular to the firstaxis.
 4. The method of claim 1, wherein articulation of the wristassembly to orient the end effector further comprises: controllingorientation of the second outer link and a third outer link relative toeach other by intermeshing of the second gear teeth and third gear teethrespectively associated with the second outer link and the third outerlink, rotating the second outer link and a second inner link relative toeach other about a fourth axis perpendicular to the first axis and thethird axis, the second inner link being pivotally coupled to the secondouter link, and rotating the third outer link and the second inner linkrelative to each other about a fifth axis parallel to the fourth axisand offset from the fourth axis.
 5. A method of using a medicalinstrument comprising: applying a distally-directed orproximally-directed load via a drive member to an end effector coupledto an elongated shaft via a wrist assembly so as to actuate the endeffector; and reacting the distally-directed or proximally-directed loadto an inner link of the wrist assembly that is pivotally coupled to afirst outer link and a second outer link, wherein the wrist assembly isactuatable via drive cables and reacting the load maintains the firstouter link interfaced with the second outer link in the absence oftension in the drive cables.
 6. The method of claim 5, wherein applyingthe distally-directed or proximally directed load actuates a jawmechanism of the end effector.
 7. The method of claim 5, wherein theshaft is elongated about a first axis and the method further comprisesorienting the end effector relative to the shaft by articulating thewrist assembly about a second axis perpendicular to the first axis. 8.The method of claim 7, wherein articulating the wrist assembly comprisetensioning one or more of the drive cables.
 9. The method of claim 7,wherein articulating the wrist assembly comprises rotating the firstouter link and the second outer link relative to each other byintermeshing first gear teeth of the first outer link with second gearteeth of the second outer link.
 10. A method of making a wrist assemblyfor coupling an end effector to a shaft, the method comprising:pivotally coupling an inner link with a first outer link by inserting afirst pair of protruding journals of an inner link into a first pair ofcomplementary journal bearings of a first outer link; pivotally couplingthe inner link with a second outer link by inserting a second pair ofprotruding journals of the inner link into a second pair of journalbearings of a second outer link; intermeshing first gear teeth of thefirst outer link with second gear teeth of the second outer link; androuting drive cables configured to articulate the first outer link andsecond outer link relative to each other through the first outer linkand second outer link.
 11. The method of claim 10, wherein pivotallycoupling the inner link with the first outer link comprises insertingthe first pair of protruding journals of a first inner link portion ofthe inner link, and wherein pivotally coupling the inner link with thesecond outer link comprises inserting the second pair of protrudingjournals of a second inner link portion of the inner link.